Ceramic locking outlet with improved grounding

ABSTRACT

The present invention relates to an improved electrical receptacle, particularly to a single locking receptacle, adapted for locking blades inserted therein. All of the terminal assemblies of the device are made from the same parts but are capable of receiving numerous different forms of locking blades. Such assemblies are made by applying different secondary operations to an adaptor portion of a single form of blank. A grounding to a mounting strap is achievable by a grounding screw mounted through the mounting plate and threaded into the adaptor portion of a terminal assembly.

United States Patent Martin [451 Apr. 25, 1972 [54] CERAMIC LOCKING OUTLET WITH 3,083,347 3/1963 Fahey ..339/88 c IMPROVED GROUNDING 3,315,210 4/1967 Cull ..339/32 R [72] Inventor: Robert L. Martin, Cranston, RI. primary Champion 73 Assi nee: General Electric Com an Assistant Examiner-Robert A. Hafer I g p y Attorney-Paul E. Rochford, Frank L. Neuhauser, Oscar B. [22] Fll di Ju 3 1970 Waddell and Joseph B. Forman [2l] Appl. No.: 51,225 ABSTRACT [52] U S Cl 339/14 R 339/88 R 339/188 R The present invention relates to an improved electrical recep- [51] tacle, particularly to a single locking receptacle, adapted for [58] Fieid 339/14 42 88 [88 C locking blades inserted therein All of the terminal assemblies 192 5 164 of the device are made from the same parts but are capable of receiving numerous different forms of locking blades. Such assemblies are made by applying different secondary operations [56] References Cited to an adaptor portion of a single form of blank. A grounding to UNlTED STATES PATENTS a mounting strap is achievable by a grounding screw mounted 3 066 276 1 H1962 H bb 1 339/189 through the mounting plate and threaded into the adaptor poru e eta on f terminal assemb] 3.123.423, 3/1964 Schmitt .....339/1s4 y 3.327.277 6/1967 Ramsing.... ..339/l4 R 3 Claims, 16 Drawing Figures PATENTEDAPR 2 5 1972 SHEET 10F 2 INVENTOR ROBERT L.MARTIN PATENTEDAPR25 I972 3@ 659.246

' sum 2 0F 2 INVENTOR ROBERT L. MARTIN I l W CERAMIC LOCKING OUTLET WITH IMPROVED GROUNDING The present invention relates to locking receptacles having arcuate blade openings for three and four blades and having three and four wire terminals with grounding and nongrounding capabilities. More specifically, the invention relates to a locking receptacle adapted to be made with a minimum number of parts and which is capable of serving as a receptacle for a variety of configurations of power blades.

Locking connectors are well known in the art and numerous such articles have been sold commercially for many years.

They conventionally have ceramic covers having cavities into which metal contacts are inserted. These cavities connect with arc shaped blade openings in the face of the device. The blades are also are shaped and, once inserted in the connector, may be pivoted to lock the blades in place therein.

A group of such devices has numerous different metal parts made up for the individual special connector functions involved. Also where such devices are to be grounded to the mounting strap, special connectors and special assembly and reassembly of devices is required. These arrangements of many distinct parts add to the cost of such devices.

Also, the special grounding connection reduce the utility of certain openings, terminals, rivets, and the like thus lowering the overall efficiency of such devices.

It is accordingly one object of the present invention to provide a high quality wiring device at a low cost wherein all elements retain their function where grounding capability is added to the device.

Another object is to provide a wiring device which can be employed as a grounding device or a non-grounding device.

A further object is to provide a device having a plurality of contact strip assemblies all formed from essentially the same parts.

Still another object is to provide a wiring device capable of handling high levels of power supplies in multiple phases.

Other objects will be in part apparent and in part pointed out in the description which follows.

In one of its broader aspects the wiring device article of the present invention comprises,

A porcelain insulating cover having at least three curved openings for insertion of power blades therethrough,

the curved portions of said openings being generally circularly aligned,

compartments in said cover connecting with said openings for housing terminal assemblies,

a base assembled to said cover to form an insulating housing for said wiring device,

a plurality of terminal assemblies for said device mounted in said compartments,

said assemblies having a U-shaped blade clamp attached to one end portion of a contact strip having a screw opening at the other end thereof,

the flat form of said contact strip and said U-shaped clamp being the same for all assemblies of said receptacle,

the screw terminal end of each strip being aligned along a side of the insulating housing of said device,

and the adaptor portion of said contact strip having bends therein to align said clamp with the nearest opening of the cover of said strip.

The description of how this and other aspects of the invention may be carried out will be made clearer by reference to the accompanying drawings in which:

FIG. 1 is a front elevation of a wiring device in accordance with the present invention having three blade openings in the face thereof. 7

FIG. 2 is a side elevation of the device of FIG. 1.

FIG. 3 is a back elevation of the device of FIG. 1.

FIG. 4 is a view of a device similar to that of FIG. 1 but of a device having four blade openings in its face and related internal parts.

FIG. 5 is a back elevation of the device of FIG. 4.

FIG. 6 is a detail of a partial section of FIG. 4 taken along the line 66 ofFIG. 4.

FIG. 7 is a rear elevation of the device as shown in FIG. 3 but with the back and mounting strap removed.

FIG. 8 is a rear elevation of the device as shown in FIG. 5 but with the back and strap of the device removed.

FIG. 9 is a perspective view of a contact strip as initially formed.

FIG. 10 is a similar view of a grounding version of the contact strip of FIG. 9.

FIGS. 11 through 14 are perspective views of the strip of FIG. 9 after various secondary forming operations.

FIG. 15 is a view of the strip of FIG. I0 after secondary forming operations.

FIG. 16 is an exploded perspective view of a detail of a strip and contact clamp showing the relationship of the parts joined in forming the contact strips of FIGS. 7 and 8.

Referring now specifically to FIGS. 1 and 2 there is seen a wiring device having an insulating cover 20 of an appropriate ceramic material. The cover has side openings through which screw terminals 22 appear having screws 24 extending therethrough. On the face of the insulating cover 20 is a mounting strap 26 having a wide central aperture 28 through which the central portion of the cover 30 extends and having ends 32 with slots 34 for insertion of screws and for mounting of the device, and pairs of plaster ears 36 to assist in wall mounting of the device. Side ribs 27 are bent down from the metal of the strap along the portion where the central aperture occurs to provide strengthening of the strap and electrical continuity from one end to the other. An assembly screw 38 extends through the strap 26 from the rear of the device to hold the strap 26, cover 20, and back 44 together. Threaded hole 42 is used to mount a plate (not shown) over the device and receives the screw (also not shown) for mounting of such plate. A hole 40 is provided in strap 26 for the novel purpose of converting the device of FIGS. 1 and 2 into a grounding device in a manner explained below with reference to FIG. 6.

On the back of the device is a plastic base 44 which is provided, as best seen in FIG. 3, with openings 46 for insertion of wires into conventional wire clamps 21 mounted on the threaded portion of the screws 24 internally of the screw terminal end 22 of a contact strip.

Assembly screw 38 is seen to hold the plastic back 44 of the device against the cover 20 by being threaded through the mounting strap 26.

Referring now to FIG. 4 a device similar to that seen in FIG. 3 is illustrated and has parts corresponding to those described with reference to FIGS. 1 and 3. The like parts of FIGS. 4 and 5 are numbered for convenience of description to correspond to those of FIGS. 1 and 3 with the exception that in each case the number is one hundred higher than the number of FIGS. 1 and 3.

One difference between the device of FIG. 1 and that of FIG. 4 relates to the arcuate openings in the face of the device, there being four such openings in that of FIGS. 4 and three such openings in the device of FIG. 1. Another distinction concerns the aperture 40 in the mounting strap 26 of FIG. I. In FIG. 4 and 6 it will be seen that a threaded screw 141 is present in the aperture of strap 126 corresponding to aperture 40 of strap 26 in FIG. 1. The function of the screw will be evident with reference to FIG. 6. FIG. 6 is a cross-sectional view taken along the line 6-6 of FIG. 4 in a region in which the screw 141 is located. It will be seen with reference to FIG. 6 that the screw 141 makes electrical contact with the strap 126 against which its head bears, and that it extends through an aperture in the insulating ceramic cover and is threaded into a grounding tab extension 123 of contact strip 122. It will be evident that a device formed as illustrated in FIG. 1 with no screw in the aperture 40, and with a thin knockout layer of porcelain between the strap 26 and the contact strip beneath opening 40 will have the strap 26 insulated from an underlying contact strip 22. In other words, the device is provided in a form in which the mounting strap 26 is electrically isolated from any and all of the contact strips. However, by inserting the screw 141 through the openings in the face of mounting bracket 126 a uniquely simple and highly effective grounding connection is accomplished between the mounting strap 126 and the contact strip 122 to bring the mounting strap and the grounding strip to the same electrical potential. As seen in FIG. 4 the screw 141 is of the the nonreversible type so that once threaded into place it is not feasible to remove it through use of a screwdriver but the screw will remain in place connecting the strip 122 to the strap 126.

Referring now to the FIGS. 7 and 8 the devices illustrated correspond to the devices of FIGS. 3 and 5 respectively with the back 44 and 144 respectively removed. The arrangement of the contact strip assembly is now described. One unique feature of the present invention is that all of the contact strips of the several forms shown in FIGS. 7 and 8 are made up starting with two elements. The first element is the blank of the form of contact'strip shown in FIG. 9 and the second part is the conventional U-shaped clamp 70 blade contact shown in inverted orientation at the lower portion of FIG. 16.

Referring now to FIG. 9 it is evident that there is a screw contact terminal end portion 50 having an opening 52 through which a screw may be inserted to be threaded into a wire clamp such as 21 of FIG. 7. The contact strip has an adaptor portion 56 at its mid section and has a clamp attachment end portion 58 in which are shown a pair of square openings 60 and 62. The screw terminal section 50 corresponds to the like section 22 as illustrated in the FIGS. 1 through 6 above.

A very slightly different form of the contact or terminal strip of FIG. 9 is shown in FIG. 10, the difference residing in the presence of a grounding tab 123 having a threaded aperture 125 therein where these parts correspond to the like numbered parts of the structure shown in FIG. 6. In other respects, the portions of the contact strip correspond to those shown and described in FIG. 9. With reference to the grounding tab 123 of FIG. 10 it is evident that by turning this grounding tab 123, as illustrated in FIG. 15, a structure corresponding to that shown in FIG. 6 is produced. This tabbed contact strip structure, once incorporated in a device of FIGS. 1 or 4, may be used in providing a simple convertibility of a device from one such as shown in FIG. 1 which is not grounded through the mounting strap 26, to a device such as shown in FIG. 4 which is grounded through the mounting strap by the threading of screw 141 into the grounding tab 123. Observe that the hole 40 at the upper right hand corner of FIG. 1 is aligned with the contact assembly in the upper left hand comer of FIG. 7 as the figures are front and back views of the same device. Similarly, the screw 141 of FIG. 4 is a aligned with the assembly in the upper left of FIG. 8.

Returning now to FIG. 9 the adaptor portion 56 is seen to be in the plane of the remainder of the contact strip of FIG. 9 and to be in a form in which the strip is economically stamped or otherwise produced from a flat stock. After initial formation in this way the contact strip may be formed into any of the forms shown in FIGS. 11 through 14 by secondary forming operations and each of these is described in turn at this point.

Referring now to FIGS. 8 and 11 it is evident that the screw terminal portion 50 may be disposed, as is shown in the assembly in the lower left hand portion of FIG. 8, in a position parallel to the sides 70 or the top cover portion of the device. The cover portion is the only element of the housing illustrated in FIG. 8. The adaptor portion 56 of a contact assembly of the lower left hand corner of FIG. 8 is seen from FIG. 8 to correspond in its alignment to the adaptor portion of FIG. 11. It is further seen that the end portion 58 of the contact assembly in the lower left hand corner of FIG. 8 is also aligned as this portion is seen in FIG. 1 l.

The form of contact strip of FIG. 11 is formed from that of FIG. 9 by bending the adaptor portion along a line generally parallel to the long dimension of the contact strip. This brings the clamp mounting end 58 into an alignment generally normal to the screwterminal end 50. Similarly the contact assembly in the upper right hand corner of the FIG. 8 is seen to have a contact strip in the form of the contact strip seen in FIG. ll.

Referring now to FIG. 12 it will be seen that this form of the contact strip results from a second bend in the adaptor portion in additionto that madein converting the strip of FIG. 9 into the form seen in FIG. 11 and that this bend is made in the adaptor portion 56 at about right angles to the first bend. The

contact strip in this form corresponds to the form shown in the contact assembly in the lower left hand portion of FIG. 7. Accordingly, although the contact strip itself is essentially formed from the structure shown in FIG. 9 when bent as shown in FIG. 12 and assembledwith a contact clamp, the assembly fits into a cavity of a distinctly different shape within the lower left hand corner of the cover of FIG. 7 and constitutes a part essentially distinct from that shown in the lower left hand portion of FIG. 8. A further distinction is that the U- clamp mounted to the assembly in the lower left hand corner of FIG. 8 is mounted in hole 62 of the clamp attachment portion, whereas the U-clamp mounted in the structure in the lower left hand corner of FIG. 7 is mounted in the hole 60 of this structure. In addition these clamps are turned at different angles relative to the clamp mounting ends of the respective assemblies. This angular orientation of the clamp itself provides an additional degree of variability of the individual contact assemblies.

Referring now to FIG. 13 it will be seen that a structure similar to that of FIG. 11 is provided but the adaptor portion of FIG. 13 structure has a first bend in a direction opposite to that of the bend of FIG. 11 structure. After receiving the first right angle bend as shown in FIG. 13 the same part can be further bent to angle the clamp mounting end 58 at an appropriate angle with reference to the screw terminal portion 50 so that the structure takes the form shown in the lower right hand comer of FIG. 7. Once in this configuration the U- clamp is attached in the hole 60 as shown in the lower right hand portion of FIG. 7 to give the assembly a distinctive form necessary for specific requirements of the device of FIG. 7. The contact strip of this assembly is formed from the element taught in FIG. 9 and this strip of FIG. 9 is essentially the same part as is used in the forming of all of the connector strip elements of the various contact strip assemblies.

It will be seen that the assembly shown in the upper left hand corner of FIG. 7 starts out as the part shown in FIG. 11.

It is bent to the left rather than to the right as is shown in FIG. 12. This same part of FIG. 1 1 may be bent further to the left as in the assembly shown in the upper left hand corner of FIG. 8, and still further to the left in the contact assembly shown on the lower right hand corner of FIG. 8.

Accordingly, it is apparent that there is a unique capability provided pursuant to this invention in the formation of a substantial array of contact strip assemblies starting with a single blank form by the bending of this contact through an adaptor mid portion thereof and the assembly thereto of a U-clamp lead contact.

What is claimed is:

1. An electrical receptacle comprising a porcelain insulating cover having an orificed portion, said portion having at least three curved openings therein for insertion of power blades therethrough,

and having a corresponding member of contact assembly compartments connecting with said openings,

the curved portions of said openings being generally circularly aligned,

a base assembled to said cover and forming therewith an insulating housing for said wiring device,

a terminal assembly disposed in each compartment, said assembly having a U-shaped blade clamp attached to one end of a contact strip and having a screw terminal at the other end,

said contact strip being initially of the identical form for'all terminal assemblies of said receptacle,

said contact strips being comprised initially of flat sheets of metal, thesheets of metal having a mid section located between the screw terminal and the clamp end of the strip, each sheet mounted on the receptacle being bent at the width of said cover, and metal flanges bent down along the longitudinal edges of the central portion of said bracket.

3. The device of claim 2 wherein a trough hole is provided in the strap aligned with a threaded hole in a contact strip within the insulating housing, and a weakened wall portion in said porcelain cover between the trough hole and the threaded hole. 

1. An electrical receptacle comprising a porcelain insulating cover having an orificed portion, said portion having at least three curved openings therein for insertion of power blades therethrough, and having a corresponding member of contact assembly compartments connecting with said openings, the curved portions of said openings being generally circularly aligned, a base assembled to said cover and forming therewith an insulating housing for said wiring device, a terminal assembly disposed in each compartment, said assembly having a U-shaped blade clamp attached to one end of a contact strip and having a screw terminal at the other end, said contact strip being initially of the identical form for all terminal assemblies of said receptacle, said contact strips being comprised initially of flat sheets of metal, the sheets of metal having a mid section located between the screw terminal and the clamp end of the strip, each sheet mounted on the receptacle being bent at at least one angle along its mid section to align the screw terminal with a side of the insulated housing and the corresponding clamp means with the nearest opening in the cover of the housing.
 2. The device of claim 1 wherein a metal bracket is disposed over the face of the cover, wherein the orificed portion of said cover extends through a centrally disposed hole through said bracket, the width of said hole being approximately equal to the width of said cover, and metal flanges bent down along the longitudinal edges of the central portion of said bracket.
 3. The device of claim 2 wherein a trough hole is provided in the strap aligned with a threaded hole in a contact strip within the insulating housing, and a weakened wall portion in said porcelain cover between the trough hole and the threaded hole. 